I have.
Officially GMH shows the followinmg for the Rear compartment
Fuel tank filler neck, rear compartment interior painted Black 578-4149.(578 would be a reasonably flat black). All except XU1 which was painted Black 599-364 or Black 222-6459. this is Warrigul Black but flat not gloss. I can not tell you what 364 is but it must date back to the 50s or 60s.
This is what Engineering released on LJ I cannot say what the plants actually did.
Just so you know the LC was - Fuel tank filler neck, rear compartment finished in Black 299-9187 or Box Black 599-5275. 9187 was painted under the front fenders, side rails, bumper brackets and visible part of the fuel tank.